The objective of this case-control study is to determine the magnitude of the association between malignant melanoma and a comprehensive set of possible risk factors, some of which previously have not received quantitative epidemiologic analysis. To accomplish this we will analyze data collected at New York University Medical Center on approximately 650 cases and twice as many controls. The effects of potential confounding factors will be removed primarily by stratification. A composite risk factor score will be developed for the purpose of identifying high risk populations, at whom future monitoring for malignant melanoma could be directed. Significant positive associations found in this study, if corroborated by others, may also identify behavior which, if modified, could result in a decreased incidence of disease.